Latch mechanism



April 20, 1 6 s. H. SCHWARTZ 3,179,456

LATCH MECHANISM Filed Feb. 11, 1963 2 Sheets-Sheet 1 V INVENTOK 60/271/9/ A @r/M/Qr/z 53 g BY TORNE YS April 20, 1965 s. H. SCHWARTZ 3,179,456

LATCH MECHANISM Filed Feb. 11, 1963 2 Sheets-Sheet 2 A'I'TORNEYS United States Patent 3,179,456 LATCH MECHANISM Samuel H. Schwartz, Deerfield, 111., assignor to The Dole Valve Company, Morton Grove, 111., a corporation of Illinois Filed Feb. 11, 1963, Ser. No. 257,566 3 Claims. (Cl. 292-444) This invention relates to latch. mechanisms and more particularly to a positive action latch for use as a safety device on washing machines or the like.

A number of devices have been proposed for use on an automatically controlled machine such as a washing machine to prevent the lid from being opened while the machine is running. It has been found, however, that these devices have added significantly to the cost of the machine, or have not proven to be reliable under all circumstances. Quite often these devices are actuated by the timing system of the machine and thus are subject to the failures of the timing system-such as remaining operated when the machine is between cycles, or the like. In thos'e devices which are responsive to the speed of the machine, many tend to be over-sensitive and oscillate if the machine speed varies a slight amount in the normal speed range due to overloading or the like.

It is therefore an object of this invention to provide a latch mechanism for the lid of an automatically controlled machine such as a washing machine which will lock the lid in its closed position while the machine is operating.

It is a further object of this invention to provide a latch mechanism for the lid of a device such as a washing machine which is responsive to the speed of the machine.

It is a further object of this invention to provide a latch mechanism utilizing a linkage arrangement having a break point or over-center point which prevents the mechanism from being released upon slight variations of the speed of the machine.

Briefly, the embodiment of the invention described herein comprises a latch mechanism for use on an auto .matic washing machine, or the like, to prevent the lid from being opened while the machine is operating. The latch mechanism is actuated by a pneumatic piston. A pneumatic pump operating from a cam on the tub drive shaft furnishes suflicient air pressure to trip the latch when the drive shaft has attained a predetermined speed.

The latch is constructed such that it has an over-center position or break point which prevents engagement of the latch until the tub has attained a predetermined speed, and also prevents release of the latch until the tub speed has dropped a significant amount below the trip speed. In this manner, oscillation of the latch is prevented.

The invention will be more fully understood from the following detailed description of an embodiment thereof:

On the drawings:

FIGURE 1 is an elevation view of a washing machine and lid. Also shown is the latch mechanism of the instant case including the pneumatic piston, the pneumatic pump which furnishes air pressure to the latch piston, and the cam which drives the pneumatic pump. The latch is shown in its extended or lid latched position.

FIGURE 2 is a sectional view of the latch mechanism shown in its extended or its latched position.

FIGURE 3 is a sectional view of the latch mechanism in its retracted position.

FIGURE 4 is a sectional View of the pneumatic pump.

Referring now to the drawings, in FIGURE 1, it is seen that a cam 25 extends from the spindle 24 which carries a tub 45. This cam 25 engage a plunger 26 of a pneumatic pump 30. Notice that the plunger 26 is biased against the cam 25 by a spring 39. As shown in 3,179,456 Patented Apr. 20, 1965 FIGURE 4, air is drawn into the pump 30 through an inlet 29 and a check valve 37, compressed by means of a diaphragm 27 and expelled through a check valve 38 and a hose 28. The hose 28 is connected to a pressure chamber 40 (shown in FIGURES 2 and 3) of a pneumatic piston 18, which has an operating rod 11 extend ing therefrom. A spring 36 encircles the operating rod 11 and rests against a bracket 48 to bias a diaphragm 31 upward. Referring particularly to FIGURE 3, when a predetermined air pressure has been created in the chamber 40 by the pump 30, the diaphragm .31 will push the operating rod 11 downward, pivoting a link 10 about a point 13. The links 10 and 12 are coupled together by a spring 32. A tab 14 on the link 10 holds one end of the spring 32 and a tab 33 on the link 12 holds the other end. The link 12 pivots about a point 34 (behind the spring 32) and is secured to a latch slider 16 by a square pin 15 which fits in a vertical slot 35 in the slide 16. The slider 16 has two elongated slots 41 and 42 formed therein. A pair of pins 43 and 44, extending from a bracket on the frame of the machine, are received in those slots. Rectilinear movement of the slider 16 is thus limited by the pins 43 and 44. It is seen that as the link 10 pivots, the tab 14 moves in an are indicated at Z. The result of such movement is shown in FIG- URE 2, where the link 12 has been pivoted clockwise about the point 34, moving the slider 16 to the right to its extended position. Meanwhile, the tab 14 on the link v the tab 33 and the pivot 34 and extended upward along link 12-the point where the tab 14 passes this line X is a break point. In other words, once the tab 14 passes this break point-going in either direction, the spring 32 pulls the link 12 clockwise or counterclockwise (moving the slider 16 to its extended or its retracted position respectively). Rectilinear movement of the latch member 16 is therefore effected whenever the point of spring connection (tab 14) on the lever 10 is to one side or the other of this straight line X which extends through the pivot 34 and the point of spring connection (tab 33) on the link 12. In this particular embodiment, straight line constitutes the longitudinal axis of the link 12.

It is noticed, however, that there is some latitude of movement of the tab 14 on either side of this break point-- that is to say, some movement of the tab 14 is permitted before the slider 16 is extended or retracted. This lost motion of the tab 14 is employed most advantageously when the slider 16 is in its extended position. For example, if the air pressure in the chamber 40 varies slightly and the link 10 is allowed to pivot clockwise a short way, the slider 16 will not be retracted. It is only when there has been a considerable drop in air pressure within the chamber 40, and the tab 14 on the link 10 is allowed to pivot clockwise past the break point, that the slider 16 is retracted. This arrangement assures that unnoticed variations in tub speed will not cause the slider 16 to oscillate. By employing various strength springs, the air pressure required in the piston 18 to arrive at the break point can be varied. In other words, by employing a very weak spring 32, the slider 16 would be closely responsive to slight changes in the air pressure in the cylinder 18. On the other hand, a strong spring 32 can be used if it is desired to make the slider 16 responsive only to relatively high air pressure in the cylinder 18. In this latter instance, however, the slider 16 would remain extended until the pressure in the chamber 40 is quite low.

Therefore, it is noted that the latching mechanism described herein is quite reliable in operation and contributes significantly to the safety of an automatically controlled machine such as a washing machine. In addition, the latching mechanism operates independently of other controls on the machine, and adds only a relatively small amount to the total cost of the machine.

While I have described the above principles of my invention in connection with a specific embodiment, it is to be clearly understood that this description was made only by way of example and not as a limitation to the scope and spirit of my invention as hereinafter claimed.

I claim as my invention:

1. A pneumatically actuatable latch comprising:

(a) a support,

7 (b) a latch member slidably mounted for rectilinear movement within said support,

() anelongated link pivotally mounted intermediate sits ends on said support and having a first end pivotally connected to said latch member,

(d) a lever pivotally mounted intermediate its ends on said support, and having an end positioned adjacent said link on the opposite side of said link pivot from the other end of said link,

(e) spring means interconnecting the adjacent ends of said lever and link,

(f) and pneumatic means cooperable with the other end of said lever for effecting pivotal movement thereof to move the spring connection point on said lever on one side or the other of a straight line intersecting the point of pivotal mounting of said link on said support and the point of spring connection on said link.

2. A latching arrangement for the lid of an automatically controlled machine having a high speed operating shaft, said latching arrangement comprising:

(a) a support,

(b) a latchmember mounted for rectilinear move ment on said support, said latch member movable in and extended position and a retracted position relative to an aperture in said lid,

(c) a cam on said high speed shaft,

, (d) a fluid pump operable by said cam,

(e) a piston including a chamber across which a movable diaphragm extends, and including an operating rod secured to said movable diaphragm,

(1'') said operating rod having a rest position and an actuated position,

(g) means biasing said operating rod towards its rest position,

(Ii) transmission means connecting said fluid pump with said chamber,

(i) resilient means,

(j) a link pivotally mounted intermediate its ends on said support and having one end pivotally connected to said latch member, and the other end attached to said resilient means,

(k) a lever pivotally mounted intermediate its ends on said support and having one end secured to said operating rod, and the other end having a tab thereon to which is secured said resilient means,

(I) said lever so positioned that upon pivoting, said tab moves from a first side of an imaginary line through the pivot of said link and the point on said link to which said resilient means is connected, through break point, to a second side of said imaginary line,

(In) said link positioned such that when said tab rests on said first side of said line, said link holds said latch member in its retracted position, and when said tab rests on said second side of said line, said link holds said latch member in its extended position through said aperture in said lid to securely lock said lid in its closed position,

(11) whereby when said tab rests on one side or the other of said break point, said lever may be pivoted slightly before said break point is reached to define a lost motion condition.

3. A latching arrangement for the lid of an automatically controlled machine having a high speed operating shaft, said latching arrangement comprising:

(a) a support,

(b) a latch member mounted for rectilinear movement on said support, said latch member movable in an extended position and a retracted position relative to an aperture in said lid,

(c) resilient means,

(d) a link pivotally mounted intermediate its ends on said support and having one end pivotally connected to said latch member and the other end attached to said resilient means,

(e) means responsive to the speed of said operating shaft, said means including an arm,

( a lever pivotally mounted intermediate its ends on said support, and having one end secured to said arm, and the other end having a tab thereon to which is secured said resilient means,

(g) said lever so positioned that upon pivoting, said tab moves from a first side of an imaginary line through the pivot of said link and the point on said link to which said resilient means is connected through a break point, to a second side of an imaginary line,

([1) said link positioned such that when said tab rests on said first side of said line, said link holds said latch member in its retracted position, and when said tab rests on said second side of said line, said link holds said latch member in its extended position through said aperture in said lid to securely lock said lid in its closed position,

(i) whereby when said tab rests on one side or the other of said break point, said lever may be pivoted slightly before said break point is reached to define a lost motion condition. I

' References Cited by the Examiner UNITED STATES PATENTS 1,989,213 1/35 Schenck 192-136 2,031,664 2/36 Miller 292-167 2,242,707 5/41 Haynes 292-144 2,359,960 10/44 Anderson 74-55 2,550,392 4/51 Venning 74-55 2,993,080 7/61 OConor et a1. 192136 FOREIGN PATENTS 246,563 5/ 12 Germany. 207,403 11/323 Great Britain.

M. HENSON WOOD, J R., Primary Examiner.

ALBERT H. KAMPE, Examiner. 

1. A PNEUMATICALLY ACTUATABLE LATCH COMPRISING: (A) A SUPPORT, (B) A LATCH MEMBER SLIDABLY MOUNTED FOR RECTILINEAR MOVEMENT WITHIN SAID SUPPORT, (C) AN ELONGATED LINK PIVOTALLY MOUNTED INTERMEDIATE ITS END ON SAID SUPPORT AND HAVING A FIRST END PIVOTALLY CONNECTED TO SAID LATCH MEMBER, (D) A LEVER PIVOTALLY MOUNTED INTERMEDIATE ITS ENDS ON SAID SUPPORT, AND HAVING AN END POSITIONED ADJACENT SAID LINK ON THE OPPOSITE SIDE OF SAID LINK PIVOT FROM THE OTHER END OF SAID LINK, (E) SPRING MEANS INTERCONNECTING THE ADJACENT ENDS OF SAID LEVER AND LINK, (F) AND PNEUMATIC MEANS COOPERABLE WITH THE OTHER END OF SAID LEVER FOR EFFECTING PIVOTAL MOVEMENT THEREOF TO MOVE THE SPRING CONNECTION POINT ON SAID LEVER ON ONE SIDE OR THE OTHER OF A STRAIGHT LINE INTERSECTING THE POINT OF PIVOTAL MOUNTING OF SAID LINK ON SAID SUPPORT AND THE POINT OF SPRING CONNECTION ON SAID LINK. 